Non-invasive determination of electromechanical time intervals of cardiac cycle using abdominal ECG and Doppler ultrasound signals from fetal hearts

Fetal ECG and Doppler ultrasound signals provide clinically significant information concerning the physiological state of a fetus. In this study, we propose a non-invasive system to recognize the timings of fetal cardiac events on the basis of analysis of fetal ECG and Doppler ultrasound signal together. Fetal ECG was extracted from transabdominal ECG (10 normal subjects, 38-41 weeks of gestation) using blind source separation with the reference signal. Multiresolution wavelet analysis enabled the frequency contents of the Doppler signals to be linked to the opening and closing of the heartpsilas valves (Aortic and mitral). The time intervals from R peak of fetal ECG to opening and closing of aortic valve were found to be 99.16plusmn22.07 (msec) and 222.70plusmn21.83 (msec) respectively. The time intervals from R peak to opening and closing of mitral valve were found to be 305.32plusmn22.71 (msec) and 37.84plusmn18.23 (msec) respectively.